From 08dc9bf01302aa7d9a75efca24de1a9b19ec5c9e Mon Sep 17 00:00:00 2001 From: =?utf8?q?Rafa=C5=82=20D=C5=82ugo=C5=82=C4=99cki?= Date: Sat, 21 Jun 2014 07:21:49 +0200 Subject: [PATCH] Make opening/closing/releasing resources available from signal handler. --- src/process1.c | 46 +++++++++++++++++++++++------------ src/process2.c | 66 ++++++++++++++++++++++++++++++-------------------- src/process3.c | 37 ++++++++++++++++++---------- 3 files changed, 94 insertions(+), 55 deletions(-) diff --git a/src/process1.c b/src/process1.c index b500483..ad4b911 100644 --- a/src/process1.c +++ b/src/process1.c @@ -11,22 +11,44 @@ /** If buffer is too small to hold entire string, it is incremented by this value */ #define BUFFER_STEP 16 +/** Buffer used to store line of characters */ +char * buffer = NULL; + +/** Named pipe used to communnicate with process2 */ +char * write_pipe = "/tmp/process1pipe"; + +/** File descriptor of pipe */ +int file_descriptor; + /** * Handler for signals. */ void sig_handler(int signo) { if (signo == SIGUSR1) { - fprintf(stderr, "[%s] SIGUSR1!\n", "process1"); + fprintf(stderr, "[%s] Received SIGUSR1!\n", "process1"); } - else if (signo == SIGUSR2) { - fprintf(stderr, "[%s] SIGUSR2!\n", "process1"); + else if (signo == SIGQUIT) { + fprintf(stderr, "[%s] Received SIGQUIT!\n", "process1"); + fprintf(stderr, "[%s] > Releasing resources\n", "process1"); + close(write_pipe); + unlink(write_pipe); + + if (buffer) { + free(buffer); + buffer = NULL; + } + exit(0); } else if (signo == SIGINT) { - fprintf(stderr, "[%s] SIGINT!\n", "process1"); + fprintf(stderr, "[%s] Received SIGINT!\n", "process1"); + fprintf(stderr, "[%s] > Closing pipe\n", "process1"); + close(write_pipe); } else if (signo == SIGCONT) { - fprintf(stderr, "[%s] SIGCONT!\n", "process1"); + fprintf(stderr, "[%s] Received SIGCONT!\n", "process1"); + fprintf(stderr, "[%s] > Opening pipe\n", "process1"); + file_descriptor = open(write_pipe, O_WRONLY); } } @@ -38,9 +60,6 @@ int main(void) { /** Currently fetched from stdin character */ int c; - /** Buffer used to store line of characters */ - char * buffer = NULL; - /** Current buffer length*/ int buffer_length = 0; @@ -53,12 +72,6 @@ int main(void) { */ char * tmp = NULL; - /** Named pipe used to communnicate with process2 */ - char * write_pipe = "/tmp/process1pipe"; - - /** File descriptor of pipe */ - int file_descriptor; - fprintf(stderr, "[%s] Init!\n", "process1"); /** @@ -67,8 +80,8 @@ int main(void) { if (signal(SIGUSR1, sig_handler) == SIG_ERR) { fprintf(stderr, "can't catch SIGUSR1\n"); } - if (signal(SIGUSR2, sig_handler) == SIG_ERR) { - fprintf(stderr, "can't catch SIGUSR2\n"); + if (signal(SIGQUIT, sig_handler) == SIG_ERR) { + fprintf(stderr, "can't catch SIGQUIT\n"); } if (signal(SIGINT, sig_handler) == SIG_ERR) { fprintf(stderr, "can't catch SIGINT\n"); @@ -137,6 +150,7 @@ int main(void) { } } while(c != EOF); + /* Release resources in normal program flow exit. */ close(write_pipe); unlink(write_pipe); diff --git a/src/process2.c b/src/process2.c index 7ae70ff..2b9a6f3 100644 --- a/src/process2.c +++ b/src/process2.c @@ -1,4 +1,6 @@ #include +/* exit.. */ +#include /* open/read/write/close */ #include @@ -9,22 +11,45 @@ /** If buffer is too small to hold entire string, it is incremented by this value */ #define BUFFER_STEP 16 +/** Named pipe used to communicate with process1 */ +char * read_pipe = "/tmp/process1pipe"; + +/** Named pipe used to communicate with process3 */ +char * write_pipe = "/tmp/process2pipe"; + +/** Descriptor of input pipe */ +int read_descriptor; + +/** Descriptor of output pipe */ +int write_descriptor; + /** * Handler for signals. */ void sig_handler(int signo) { if (signo == SIGUSR1) { - fprintf(stderr, "[%s] SIGUSR1!\n", "process1"); + fprintf(stderr, "[%s] Received SIGUSR1!\n", "process2"); } - else if (signo == SIGUSR2) { - fprintf(stderr, "[%s] SIGUSR2!\n", "process1"); + else if (signo == SIGQUIT) { + fprintf(stderr, "[%s] Received SIGQUIT!\n", "process2"); + fprintf(stderr, "[%s] > Releasing resources\n", "process2"); + close(read_descriptor); + close(write_descriptor); + unlink(write_descriptor); + exit(0); } else if (signo == SIGINT) { - fprintf(stderr, "[%s] SIGINT!\n", "process1"); + fprintf(stderr, "[%s] Received SIGINT!\n", "process2"); + fprintf(stderr, "[%s] > Closing pipes\n", "process2"); + close(read_descriptor); + close(write_descriptor); } else if (signo == SIGCONT) { - fprintf(stderr, "[%s] SIGCONT!\n", "process1"); + fprintf(stderr, "[%s] Received SIGCONT!\n", "process2"); + fprintf(stderr, "[%s] > Opening pipes\n", "process2"); + read_descriptor = open(read_pipe, O_RDONLY); + write_descriptor = open(write_pipe, O_WRONLY); } } @@ -33,18 +58,6 @@ void sig_handler(int signo) * and pass the value to process3. */ int main(void) { - /** Named pipe used to communicate with process1 */ - char * read_pipe = "/tmp/process1pipe"; - - /** Named pipe used to communicate with process3 */ - char * write_pipe = "/tmp/process2pipe"; - - /** Descriptor of input pipe */ - int read_descriptor; - - /** Descriptor of output pipe */ - int write_descriptor; - /** * Buffer used for storing data from input pipe. * Data is stored in chunks of BUFFER_STEP size. @@ -59,13 +72,6 @@ int main(void) { /** Stores number of bytes read from input pipe in current iteration */ ssize_t count = 0; - /* Reading from process1 */ - read_descriptor = open(read_pipe, O_RDONLY); - - /* Writing to process2 */ - mkfifo(write_pipe, 0666); - write_descriptor = open(write_pipe, O_WRONLY); - int number_of_characters = 0; fprintf(stderr, "[%s] Init!\n", "process2"); @@ -76,8 +82,8 @@ int main(void) { if (signal(SIGUSR1, sig_handler) == SIG_ERR) { fprintf(stderr, "can't catch SIGUSR1\n"); } - if (signal(SIGUSR2, sig_handler) == SIG_ERR) { - fprintf(stderr, "can't catch SIGUSR2\n"); + if (signal(SIGQUIT, sig_handler) == SIG_ERR) { + fprintf(stderr, "can't catch SIGQUIT\n"); } if (signal(SIGINT, sig_handler) == SIG_ERR) { fprintf(stderr, "can't catch SIGINT\n"); @@ -86,6 +92,13 @@ int main(void) { fprintf(stderr, "can't catch SIGCONT\n"); } + /* Reading from process1 */ + read_descriptor = open(read_pipe, O_RDONLY); + + /* Writing to process2 */ + mkfifo(write_pipe, 0666); + write_descriptor = open(write_pipe, O_WRONLY); + while(1) { /* Read data from input pipe */ count = read(read_descriptor, buffer, BUFFER_STEP); @@ -107,6 +120,7 @@ int main(void) { } } + /* Release resources in normal program flow exit. */ close(read_descriptor); close(write_descriptor); unlink(write_descriptor); diff --git a/src/process3.c b/src/process3.c index 8b4f826..e75a4fb 100644 --- a/src/process3.c +++ b/src/process3.c @@ -1,27 +1,43 @@ #include +/* exit.. */ +#include + /* open/read/write/close */ #include /* Signals handling.. */ #include +/** Named pipe used to communicate with process2 */ +char * read_pipe = "/tmp/process2pipe"; + +/** Descriptor of input pipe */ +int read_descriptor; + /** * Handler for signals. */ void sig_handler(int signo) { if (signo == SIGUSR1) { - fprintf(stderr, "[%s] SIGUSR1!\n", "process1"); + fprintf(stderr, "[%s] Received SIGUSR1!\n", "process3"); } - else if (signo == SIGUSR2) { - fprintf(stderr, "[%s] SIGUSR2!\n", "process1"); + else if (signo == SIGQUIT) { + fprintf(stderr, "[%s] Received SIGQUIT!\n", "process3"); + fprintf(stderr, "[%s] > Releasing resources\n", "process3"); + close(read_descriptor); + exit(0); } else if (signo == SIGINT) { - fprintf(stderr, "[%s] SIGINT!\n", "process1"); + fprintf(stderr, "[%s] Received SIGINT!\n", "process3"); + fprintf(stderr, "[%s] > Closing pipe\n", "process2"); + close(read_descriptor); } else if (signo == SIGCONT) { - fprintf(stderr, "[%s] SIGCONT!\n", "process1"); + fprintf(stderr, "[%s] Received SIGCONT!\n", "process3"); + fprintf(stderr, "[%s] > Opening pipe\n", "process2"); + read_descriptor = open(read_pipe, O_RDONLY); } } @@ -30,12 +46,6 @@ void sig_handler(int signo) * grabbed data to the standard output. */ int main(void) { - /** Named pipe used to communicate with process2 */ - char * read_pipe = "/tmp/process2pipe"; - - /** Descriptor of input pipe */ - int read_descriptor; - /** Buffer used for storing data from input pipe */ int buffer = 0; @@ -50,8 +60,8 @@ int main(void) { if (signal(SIGUSR1, sig_handler) == SIG_ERR) { fprintf(stderr, "can't catch SIGUSR1\n"); } - if (signal(SIGUSR2, sig_handler) == SIG_ERR) { - fprintf(stderr, "can't catch SIGUSR2\n"); + if (signal(SIGQUIT, sig_handler) == SIG_ERR) { + fprintf(stderr, "can't catch SIGQUIT\n"); } if (signal(SIGINT, sig_handler) == SIG_ERR) { fprintf(stderr, "can't catch SIGINT\n"); @@ -77,6 +87,7 @@ int main(void) { } } + /* Release resources in normal program flow exit. */ close(read_descriptor); return 0; -- 2.30.2